chore(deps): update dependency log4net to v3

Author: renovate[bot]

src/NHibernate.Search.Tests/NHibernate.Search.Tests.csproj

@@ -15,7 +15,7 @@
     <ProjectReference Include="..\NHibernate.Search\NHibernate.Search.Lucene.csproj" />
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="log4net" Version="2.0.17" />
+    <PackageReference Include="log4net" Version="3.0.2" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.10.0" />
     <PackageReference Include="NUnit" Version="3.14.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />